1. Field
The disclosure relates to an energy harvester, and more particularly, to an energy harvester that converts vibration energy into electrical energy in a frequency range with a wide bandwidth and harvests the electrical energy.
2. Description of the Related Art
Recently, a technology of harvesting energy that is in the environment has become an issue. For example, vibration energy that is generated in the environment may be converted into electrical energy using the piezoelectric effect, electrostatic effect, or electrodynamic effect, and such converted electrical energy may be harvested. An energy harvester that converts vibration energy into electrical energy and harvests the electrical energy may include a cantilever type energy harvester.
A general cantilever-type energy harvester generates electrical energy using a maximum displacement of a cantilever beam that occurs when the cantilever beam vibrates at a specific resonant frequency. The general cantilever-type energy harvester may harvest vibration energy only at a specific frequency having a narrow bandwidth. However, general vibration conditions in the environment do not include only a fixed specific frequency but include various frequencies in a predetermined range including the fixed specific frequency. Vibration energy in a predetermined frequency range may be harvested by a method using a plurality of cantilever beams having different resonant frequencies, but output power density of the harvested electrical energy may be substantially low.